Which motor and why
 

I got a 21 foot open bow currently I am thinking Chevrolet LS motor with twin turbos at about 800 hp but after talking to some guys at the boat shop, they keep telling me big block Chevy for longevity. Ls just won’t hold up to longevity. What’s your guys start on this? You guys run more of this stuff than I do especially turn in RPM in a boat I do have a set of big block aluminum log manifolds from a jet boat and I do have a tall deck, 454 block so those are my things I have laying around and I have a LQ4LS motor any thoughts or comments would be greatly appreciated on this I know it’s probably been debated to death, but I’m new to this and I’m curious and I have to have 10 posts so this is what I come up with for one of them

Lots of people have tried the LS/turbo route and I haven`t seen too many that were sucessful.
BBC is the simpler/easier way to go .

Which motor
 

Hey, thanks for your reply. Seems like a big block Chevy’s way to go.

A twin turbo LS is a lot more work and stress than a 800hp NA BBC. BBC is still king

Do we know what fails... regarding success/fail?

You might go down the (Nissan vk56) rabbit hole too.

YouTube
(Hartley Engineering)
(That Ricer Jon)

Drag guys making 2000 HP
Over Head Cams
Cheap & Cheap to build

Unknown on the endurance side ???

Which motor
 

Thanks I’m thinking bbc

What make of boat? Is it capable of handling 800 HP? What out drive are you planning on running?

I had a 21' Bryant with a 7.4L and it sat way heavy in the rear. With a full crew on board it was a pig to get onto plane. Granted it only had 330 HP but, you get what I'm eluding to.

LS platform is amazing for making horsepower but boats and cars live a completely different lifestyle. If you built a 800HP twin turbo LS and made 200 1/4 mile passes that would be considered a Very reliable setup. Now that would equate to 50 miles in a powerboat under load which may be 30-45 minutes of wide open throttle. Everybody runs their stuff differently but that could be 2 weekends for some people. It’s hard to beat the reliability of a heavy old Big Block Chevy. 7 Marine tried to do it with the 6.2 LSA and it wasn’t very reliable.

back when Ilmor was doing the V10 engines I asked one of the guys there why they didnt offer a supercharged version. the answer was that they tried but the aluminum blocks did not like extended boost. seems the block would start to move around too much so they gave up on it. he said that if they could have used the older iron blocks it would have worked but those were no longer available at the time. I would think that the same would apply to the LS if using the aluminum blocks because as stated, boats live for a long time under load vs a car. dont know what would be the result if using an iron block LS.